Microfauna

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Soybean cyst nematode and egg. Soybean cyst nematode and egg SEM.jpg
Soybean cyst nematode and egg.

Microfauna (Ancient Greek mikros "small" + Neo-Latin fauna "animal") refers to microscopic animals and organisms that exhibit animal-like qualities, and have body sizes that are usually <0.1mm. [1] [2] Microfauna are represented in the animal kingdom (e.g. nematodes, small arthropods) and the protist kingdom (i.e. protozoans). A large amount of microfauna are soil microfauna which includes protists, rotifers, and nematodes. These types of animal-like protists are heterotrophic, largely feeding on bacteria. However, some microfauna can consume other things, making them detritivores, fungivores, or even predators. [3]

Contents

Habitat

Microfauna are present in every habitat on Earth. They fill essential roles as decomposers and food sources for lower trophic levels, and are necessary to drive processes within larger organisms. Populations of microfauna can reach up to ~107 (~10,000,000) individuals g−1 (0.1g, or 1/10th of a gram), and are very common in plant litter, surface soils, and water films. [3] Many microfauna inhabit soil habitats such as nematodes. Plant parasitic nematodes inhabit the roots of various plants, while free-living nematodes live in soil water films. [3]

Microfauna also inhabit freshwater ecosystems. For example, freshwater microfauna in Australia include rotifers, ostracods, copepods, and cladocerans. [4] Rotifers are filter feeders that are usually found in fresh water and water films. They consume a variety of things including bacteria, algae, plant cells, and organic material. [3]

Tardigrades inhabit a variety of lichens and mosses. They need water in these areas to allow for gas exchange and to prevent them from desiccating. [5] Because of this they are considered aquatic. However, they have also been found in all kinds of environments that range from the deep sea to dunes. Tardigrades are considered omnivores that have specialized mouths called bucco pharyngeal apparatuses which they use to consume different microorganisms and plants in their environments. [5]

Role

The microbiome of plants includes the phyllosphere and the rhizosphere. Model of the plant microbiome (phytobiome).jpg
The microbiome of plants includes the phyllosphere and the rhizosphere.

One particular example of the role of microfauna can be seen in soil, where they are important in the cycling of nutrients in ecosystems. [6] The ecological functions of the rhizosphere can be influenced by microfauna, specifically by nematodes and protozoa who are abundant in soil. For instance, the carbon cycling within the soil can be affected by nematodes who will feed on the roots of plants, impacting the organic carbon in the soil. Similarly, soil protozoa are able to release phosphorus and nitrogen into the soil and higher trophic levels by dissolving the organic material and nutrients available. [7]

Soil micro-fauna can also impact microorganisms within the rhizosphere by affecting their diversity and accelerating microorganism turnover. This happens because of the microfauna's selective grazing and their ability to influence the resources within the soil. [8] For example, protozoa can help maintain the quality of the soil by grazing on soil bacteria. Through their grazing, the protozoa can help maintain populations of bacteria, allowing the bacteria to more efficiently decompose dead organic material which will improve the fertility of the soil. [9]

Soil microfauna are capable of digesting just about any organic substance, and some inorganic substances.[ citation needed ] These organisms are often essential links in the food chain between primary producers and larger species. For example, zooplankton are widespread microscopic animals and protists that feed on algae and detritus in the ocean, such as foraminifera.

Microfauna also aid in digestion and other processes in larger organisms.

Cryptozoa

The microfauna are the least understood of soil life, due to their small size and great diversity. Many microfauna are members of the so-called cryptozoa, animals that remain undescribed by science. Out of the estimated 10-20 million animal species in the world, only 1.8 million have been given scientific names, and many of the remaining millions are likely microfauna, much of it from the tropics.

Phyla

Examples of notable phyla that include some microfauna:

Similar Concepts

Macrofauna vs Microfauna

Macrofauna are organisms that are greater than 2mm in size that usually inhabit soft sediments. [12] They are also found in the benthic zone, and are suspension feeders or deposit feeders. [13] They are important to the marine food web as they are preyed upon by other organisms. Macrofauna, such as earthworms, are able to be separated into small parts through fragmentation, and are able to decompose organic matter. [14]

Size Comparison of soil organisms Size classification of soil organisms.jpg
Size Comparison of soil organisms

Microflora vs Microfauna

Microflora are organisms that reside within intestines and assist with the digestion of food. [15] In soil, there are three main groups of microflora: viruses, fungi, and bacteria.

See also

Related Research Articles

<span class="mw-page-title-main">Microorganism</span> Microscopic living organism

A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells.

<span class="mw-page-title-main">Nutrition</span> Provision to cells and organisms to support life

Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain sufficient nutrients causes malnutrition. Nutritional science is the study of nutrition, though it typically emphasizes human nutrition.

<span class="mw-page-title-main">Meiobenthos</span> Group of marine and fresh water organisms defined by their small size

Meiobenthos, also called meiofauna, are small benthic invertebrates that live in marine or freshwater environments, or both. The term meiofauna loosely defines a group of organisms by their size—larger than microfauna but smaller than macrofauna—rather than by their taxonomy. This fauna includes both animals that turn into macrofauna later in life, and those small enough to belong to the meiobenthos their entire life. In marine environments there can be thousands of individuals in 10 cubic centimeters of sediment, and counts animals like nematodes, copepods, rotifers, tardigrades and ostracods, but protists like ciliates and foraminifers within the size range of the meiobethos are also often included. In practice, the term usually includes organisms that can pass through a 1 mm mesh but are retained by a 45 μm mesh, though exact dimensions may vary. Whether an organism will pass through a 1 mm mesh also depends upon whether it is alive or dead at the time of sorting.

<span class="mw-page-title-main">Fauna</span> Set of animal species in any particular region and time

Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is flora, and for fungi, it is funga. Flora, fauna, funga and other forms of life are collectively referred to as biota. Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess Shale fauna". Paleontologists sometimes refer to a sequence of faunal stages, which is a series of rocks all containing similar fossils. The study of animals of a particular region is called faunistics.

In agriculture and gardening, a beneficial organism is any organism that benefits the growing process, including insects, arachnids, other animals, plants, bacteria, fungi, viruses, and nematodes. Benefits include pest control, pollination, and maintenance of soil health. The opposite of beneficial organisms are pests, which are organisms deemed detrimental to the growing process. There are many different types of beneficial organisms as well as beneficial microorganisms. Also, microorganisms have things like salt and sugar in them. Beneficial organisms include but are not limited to: Birds, Bears, Nematodes, Insects, Arachnids, and fungi. The ways that birds and bears are considered beneficial is mainly because they consume seeds from plant and spread them through feces. Birds also prey on certain insects that eat plants and hinder them from growing these insects are known as non beneficial organisms. Nematodes are considered beneficial because they will help compost and provide nutrients for the soil the plants are growing in. Insects and arachnids help the growing process because they prey on non beneficial organisms that consume plants for food. Fungi help the growing process by using long threads of mycelium that can reach very long distances away from the tree or plant and bring water and nutrients back to the tree or plant roots.

<span class="mw-page-title-main">Flora (microbiology)</span>

In microbiology, collective bacteria and other microorganisms in a host are historically known as flora. Although microflora is commonly used, the term microbiota is becoming more common as microflora is a misnomer. Flora pertains to the Kingdom Plantae. Microbiota includes Archaea, Bacteria, Fungi and Protists. Microbiota with animal-like characteristics can be classified as microfauna.

<span class="mw-page-title-main">Rhizosphere</span> Region of soil or substrate comprising the root microbiome

The rhizosphere is the narrow region of soil or substrate that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome. Soil pores in the rhizosphere can contain many bacteria and other microorganisms that feed on sloughed-off plant cells, termed rhizodeposition, and the proteins and sugars released by roots, termed root exudates. This symbiosis leads to more complex interactions, influencing plant growth and competition for resources. Much of the nutrient cycling and disease suppression by antibiotics required by plants occurs immediately adjacent to roots due to root exudates and metabolic products of symbiotic and pathogenic communities of microorganisms. The rhizosphere also provides space to produce allelochemicals to control neighbours and relatives.

Microecosystems can exist in locations which are precisely defined by critical environmental factors within small or tiny spaces.

<i>Vorticella</i> Genus of single-celled organisms

Vorticella is a genus of bell-shaped ciliates that have stalks to attach themselves to substrates. The stalks have contractile myonemes, allowing them to pull the cell body against substrates. The formation of the stalk happens after the free-swimming stage.

<span class="mw-page-title-main">Soil biology</span> Study of living things in soil

Soil biology is the study of microbial and faunal activity and ecology in soil. Soil life, soil biota, soil fauna, or edaphon is a collective term that encompasses all organisms that spend a significant portion of their life cycle within a soil profile, or at the soil-litter interface. These organisms include earthworms, nematodes, protozoa, fungi, bacteria, different arthropods, as well as some reptiles, and species of burrowing mammals like gophers, moles and prairie dogs. Soil biology plays a vital role in determining many soil characteristics. The decomposition of organic matter by soil organisms has an immense influence on soil fertility, plant growth, soil structure, and carbon storage. As a relatively new science, much remains unknown about soil biology and its effect on soil ecosystems.

<span class="mw-page-title-main">Microbial cyst</span> Resting or dormant stage of a microorganism

A microbial cyst is a resting or dormant stage of a microorganism, that can be thought of as a state of suspended animation in which the metabolic processes of the cell are slowed and the cell ceases all activities like feeding and locomotion. Many groups of single-celled, microscopic organisms, or microbes, possess the ability to enter this dormant state.

<span class="mw-page-title-main">Organisms involved in water purification</span>

Most organisms involved in water purification originate from the waste, wastewater or water stream itself or arrive as resting spore of some form from the atmosphere. In a very few cases, mostly associated with constructed wetlands, specific organisms are planted to maximise the efficiency of the process.

<span class="mw-page-title-main">Protozoa</span> Single-celled eukaryotic organisms that feed on organic matter

Protozoa are a polyphyletic group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic debris. Historically, protozoans were regarded as "one-celled animals".

Archaeobiology, the study of the biology of ancient times through archaeological materials, is a subspecialty of archaeology. It can be seen as a blanket term for paleobotany, animal osteology, zooarchaeology, microbiology, and many other sub-disciplines. Specifically, plant and animal remains are also called ecofacts. Sometimes these ecofacts can be left by humans and sometimes they can be naturally occurring. Archaeobiology tends to focus on more recent finds, so the difference between archaeobiology and palaeontology is mainly one of date: archaeobiologists typically work with more recent, non-fossilised material found at archaeological sites. Only very rarely are archaeobiological excavations performed at sites with no sign of human presence.

<span class="mw-page-title-main">Antarctic microorganism</span>

Antarctica is one of the most physically and chemically extreme terrestrial environments to be inhabited by lifeforms. The largest plants are mosses, and the largest animals that do not leave the continent are a few species of insects.

<span class="mw-page-title-main">Marine microorganisms</span> Any life form too small for the naked human eye to see that lives in a marine environment

Marine microorganisms are defined by their habitat as microorganisms living in a marine environment, that is, in the saltwater of a sea or ocean or the brackish water of a coastal estuary. A microorganism is any microscopic living organism or virus, which is invisibly small to the unaided human eye without magnification. Microorganisms are very diverse. They can be single-celled or multicellular and include bacteria, archaea, viruses, and most protozoa, as well as some fungi, algae, and animals, such as rotifers and copepods. Many macroscopic animals and plants have microscopic juvenile stages. Some microbiologists also classify viruses as microorganisms, but others consider these as non-living.

Soil microbiology is the study of microorganisms in soil, their functions, and how they affect soil properties. It is believed that between two and four billion years ago, the first ancient bacteria and microorganisms came about on Earth's oceans. These bacteria could fix nitrogen, in time multiplied, and as a result released oxygen into the atmosphere. This led to more advanced microorganisms, which are important because they affect soil structure and fertility. Soil microorganisms can be classified as bacteria, actinomycetes, fungi, algae and protozoa. Each of these groups has characteristics that define them and their functions in soil.

<span class="mw-page-title-main">Soil mesofauna</span> Invertebrates living in soil

Soil mesofauna are invertebrates between 0.1mm and 2mm in size, which live in the soil or in a leaf litter layer on the soil surface. Members of this group include nematodes, mites, springtails (collembola), proturans, pauropods, rotifers, earthworms, tardigrades, small spiders, pseudoscorpions, opiliones (harvestmen), enchytraeidae such as potworms, insect larvae, small isopods and myriapods. They play an important part in the carbon cycle and are likely to be adversely affected by climate change.

<span class="mw-page-title-main">Branches of microbiology</span> List of scientific disciplines

The branches of microbiology can be classified into pure and applied sciences. Microbiology can be also classified based on taxonomy, in the cases of bacteriology, mycology, protozoology, and phycology. There is considerable overlap between the specific branches of microbiology with each other and with other disciplines, and certain aspects of these branches can extend beyond the traditional scope of microbiology In general the field of microbiology can be divided in the more fundamental branch and the applied microbiology (biotechnology). In the more fundamental field the organisms are studied as the subject itself on a deeper (theoretical) level. Applied microbiology refers to the fields where the micro-organisms are applied in certain processes such as brewing or fermentation. The organisms itself are often not studied as such, but applied to sustain certain processes.

Microbivory is a feeding behavior consisting of eating microbes practiced by animals of the mesofauna, microfauna and meiofauna.

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